The invention relates to a conveying system for transporting workpieces, in particular workpiece carriers.
Such a conveying device for transporting workpieces is disclosed in laid-open publication DE 36 15 064 A1. This conveying device has two parallel transport tracks and a transverse conveyor disposed between them, wherein the transport tracks respectively have an outward located conveyor belt with an endless band belt guided on rollers, and a respectively inward located roller system disposed at a distance from the conveyor belt. The transverse conveyor has a support frame arranged between the parallel transport tracks, which has an immobile center piece. Respectively one pivotably located end piece constitutes a transfer station. Each one of these end pieces intersects an inward located roller system of a transport track and covers the free space between the roller system and an outward located band belt of the transport track. Respectively one lifting device is associated with the two end pieces, by means of which the end pieces can be pivoted into several different vertical positions in respect to the transport track.
When designing such transverse conveyors it is necessary that the pivot axis, around which the end pieces can be pivotably arranged, has a defined distance from the inward located roller system, so that a passage over the roller system disposed between the end pieces of the transverse conveyor is made possible. Furthermore a part-intensive embodiment in the pivot range is required, so that the band belt of the end pieces can be driven. Because of the division of the transverse conveyor into end sections and a center piece, a multitude of different belt lengths is required.
Furthermore, a conveyor device for transporting workpieces has already become known, which has two parallel transport tracks and a transverse conveyor arranged between them. This conveying device is embodied as a single band belt system. The transverse conveyor, which constitutes an inserting or removal track, has a rigid frame which can be moved up or down by means of a lifting cylinder arranged in the respective end sections.
In connection with such single band belt systems it is necessary that the workpiece be arranged on the workpiece carrier in such a way that an even force distribution acts on the belt conveyor track as well as on the inward located roller system. As soon as the load distribution of the workpiece on the workpiece carrier lies more on the roller system, an interference-free operation during inserting or delivering the workpiece carrier can no longer be assured, since the frictional force acting between the workpiece carrier and the single band belt could be reduced. For this reason the transport belt is subjected to greater wear because of friction.